This invention relates to an amplifier device.
FIG. 4 shows an example of a conventional amplifier device. In the amplifier, the output signal of a signal source 1 is supplied through an input terminal 2 to the positive input terminal (+) of a differential amplifier 3 having an amplification degree G, and the output of the differential amplifier 3 is applied to an output buffer amplifier 4 having an amplification degree A. The output of the output buffer amplifier 4 is applied through a feedback circuit 5 having an amplification degree B to the negative input terminal (-) of the differential amplifier 3 and is applied through an output terminal 6 to a load RL.
In the amplifier device thus arranged, the amount of feedback corresponds to the product of the amplification degrees of G, A and B. As the amount of feedback increases, the distortion is decreased. However, since it is necessary for the amplifier device to have a certain oscillation margin, there is an upper limit for the amount of feedback, and accordingly it is difficult to sufficiently decrease the distortion.